Hey guys just wondering if there were any pros/cons to running either? I have heard that the 5.13s are weaker due to the smaller pinion gear. Any truth to this? I am gong to be running 35's fully locked with chromoly shafts. I would say thats going to be it, but I say never say never on 37s either. This rig is primarily a trail rig not a DD, but will drive to and from the trails. It will see some rocks but nothing to the extreme. Also if my tranny ever goes I might be looking at a t-18 type transmission. To beef it up a bit. Which has a 1:1 final drive ratio, as compared to a .79:1 in the BA-10/AX-15. If that plays into it at all. I amget looking forto something deeperon than just the the rpms ect. Any underlyingengine advantages toto either? Let me know what you guys think.

Thanks

Tyler

__________________
89 YJ.. My first jeep and I won't let it go. ▀||||▀

I dunno this is really a matter of opinion and personal preference above hard unopinionated fact. I think 5.13 is alittle deep for 35's and possibly even too deep for 37's. you can get away with it but highway driving is going to be noisy at that high rpm. Since you are planning on an engine upgrade ontop of all of this in the distant future I can tell you that a stroked motor with 5.13s will be screaming bloody murder on the hiway with 35's.

I'm running a ford 9" as well, 4.56 gears and 36" tires makes my ride comfortable but noisy on the highways. If I were in your position, only running 35's initially, and a possible high-torque motor in the future, I would go 4.88.

I dunno this is really a matter of opinion and personal preference above hard unopinionated fact. I think 5.13 is alittle deep for 35's and possibly even too deep for 37's. you can get away with it but highway driving is going to be noisy at that high rpm. Since you are planning on an engine upgrade ontop of all of this in the distant future I can tell you that a stroked motor with 5.13s will be screaming bloody murder on the hiway with 35's.

I'm running a ford 9" as well, 4.56 gears and 36" tires makes my ride comfortable but noisy on the highways. If I were in your position, only running 35's initially, and a possible high-torque motor in the future, I would go 4.88.

Ok. Thank you sir. Appreciate the input

__________________
89 YJ.. My first jeep and I won't let it go. ▀||||▀

Just going by the tire size charts, 4.56 is what they say would make the ratio right. I would go lower though. I have a friend running 33's with 4.56 gears on the 6-cylinder and he feels like it is perfect. So I would think you would want a deeper gear for 35's.

I built mine for running 33's, it's the 4-cylinder. I am running 4.88 gears which is the correct final drive ratio. But accelerating from stop lights, I wish it was a little faster, I wish it had a little lower gear or lighter tires. So to compensate for the weight of the tires I would go lower than the charts say.

Hey guys just wondering if there were any pros/cons to running either? I have heard that the 5.13s are weaker due to the smaller pinion gear. Any truth to this? I am gong to be running 35's fully locked with chromoly shafts. I would say thats going to be it, but I say never say never on 37s either. This rig is primarily a trail rig not a DD, but will drive to and from the trails. It will see some rocks but nothing to the extreme. Also if my tranny ever goes I might be looking at a t-18 type transmission. To beef it up a bit. Which has a 1:1 final drive ratio, as compared to a .79:1 in the BA-10/AX-15. If that plays into it at all. I amget looking forto something deeperon than just the the rpms ect. Any underlyingengine advantages toto either? Let me know what you guys think.

Thanks

Tyler

Tyler,

Go 4.88 for a lot of reasons....

The 5.13 pinion is small. I run 5.13's was surprised how small it was. My gear guy even showed me the difference between 5.13 and 4.56 and asked if I was sure before he installed them.

After wheeling for 18 months with 5.13's I have no doubt that I will go 4.88 on my next rig.

For your tire size you would hate driving with 5.13's. Its too deep of a gear for 35's or 37's. You would have trouble getting any wheel speed at all, and sometimes you will need it. with 5.13's you might not be able to drive comfortably on the highway. or on any road. You will be able to start out in 3rd gear. I can, and have 40's.

The 5.13 pinion is small. I run 5.13's was surprised how small it was. My gear guy even showed me the difference between 5.13 and 4.56 and asked if I was sure before he installed them.

After wheeling for 18 months with 5.13's I have no doubt that I will go 4.88 on my next rig.

For your tire size you would hate driving with 5.13's. Its too deep of a gear for 35's or 37's. You would have trouble getting any wheel speed at all, and sometimes you will need it. with 5.13's you might not be able to drive comfortably on the highway. or on any road. You will be able to start out in 3rd gear. I can, and have 40's.

Go 4.88

Perfect. Thanks

__________________
89 YJ.. My first jeep and I won't let it go. ▀||||▀

im installing a set of 5.13s in my yj this weekend so ill post up how it does on 37s. but my tranny has a .69 OD so ill be running almost exactly 2000rpms at 65, which looking at my pickup with the same engine thats exactly what it runs so i dont see a problem. and yes the pinion is pretty small on the 5.13s but the shaft is the same thickness so i dont really see the problem. i ran 4.88s on 33s with a 4cyl and it did alright. so i figure if i can drive that i can do 5.13s on 37s with a better OD

i have no experience with sterlings but basically compared to a standard diff style like the danas the 9" pinions of like ratios tend to be larger with larger teeth. the 9" meshes with the ring gear in a different place. this is why the standard 9 pinion is so low and a hP is so high.